Read here. The number of major volcanic eruptions has diminished over the last two decades, resulting in a significantly cleaner stratosphere that allows more solar energy to strike the earth's surface. The net result: at least 50% of modern "global warming" is due to less volcanic activity.
"Since 1997, when Pinatubo’s aerosol settled out, the stratosphere has been exceptionally clear.....Half or more of the warming since 1995 may due to the lack of large volcanic eruptions.....That's about 0.13°C.....The remaining climate change is presumably caused by other forces, such as solar variability, El Nino, Atlantic AMO warming in 1995, lower Albedo and maybe even a little greenhouse gas."